Abstract:

In certain market situations the llJ9rkeLv_al_ue of dehydrated lu_cern can be increased
dramatically by separati~g the different levels of protein by applying a pneumatic
separation process.
The pneumatic separation method was developed by the Department of Agriculture
in the USA. In a situation where high and low level protein is needed for animal
food, air separation is not always the most effective method. The separation of
leaves and stems will generate a higher-quality product because the protein content
will be highter and will thus increase the gross income for the farmer. The market
requirements for separated lucerne requires 70% leaf content (which represents
the high protein component) at cut lengths of 60 mm, 120 mm and 150 mm.
The remaining sems (30%) will have a low protein conent.
A lucerne separation apparatus was developed for this study as a prototype in order
to determine the concept and principles of the process before the apparatus could
be commercialised. In every test, ten samples of 10 g each were collected from
three different outlets for laboratory testing. The specimens were counted microscopically
to determine the separation percentage between the high and low level
proteins. The process was then repeated in order to compile tables for determining
the optimum separation level of lucerne at a specific outl.et and speed.
The tests showed that the separation percentage of lucerne with a flower stage of
20 %, continuously performed better than the group with a flower stage of 100 %.
The best results for the separation were at the first two outlets at a speed of 350
revolutions per minute (rpm).
According to the laboratory analysis by the ARC, the protein levels of the high
potein component varied from 22,3 % to 26,23 %, which is fully acceptable to the
market, where the need is only some 20 %.
The prototype was built with the vision that a South African design can also be successfully
utilised to increase the value of lucerne.